Variable speed controls for motors



Jan. 15, 1957 A. Dl MINO 2,777,964

VARIABLE SPEED CONTROLS FOR MOTORS Filed Sept. 13, 1952 2 Sheets-Sheet 1 I N VEN TOR. AMP/901x455 0/ M/n/a Jan. 15, 1957 A. DI MINO 2,777,964

VARIABLE SPEED CONTROLS FOR MOTORS Filed Sept. 13, 1952 2 Sheets-Sheet 2 BY Fm wi i United States Patent VARIABLE SPEED CGNTROLS FOR MOTORS Alphonse Di Minn, Brooklyn, N. Y., assignor to Old Town Corporation, Brooklyn, N. Y., a corporation of New York Application September 13, 1952, Serial No. 302,565

Claims. (Cl. 31095) The present invention relates to variable speed controls for motors.

In processing various types of materials, such as for example, and not by way of limitation, paper, cloth, wire, thin metal sheeting, etc., it is often necessary to unwind the material from a supply roll thereof to subject it to a particular process, after which the material is rewound on a take-up or wind-up roll. For example, in the manufacture of carbon paper, the uncoated paper is unwound from a supply roll and passes through a device which applies a carbon coating thereto and then is rewound upon a take-up or Wind-up roll. In one apparatus of this type, provision is made for a single motor which rotates the take-up roll, the paper being unwound from the supply roll by the take-up rewind thereof. During this operation it is necessary that the paper tension between the rolls be kept within safe limits to prevent tearing of the paper between the rolls, and also to prevent damage to the coated paper on the take-up roll which may result from too tight a rewind. However, as the diameter of the rewound roll of paper increases, the speed or velocity of the paper travel between the rolls increases, whereby to increase the paper tension, as well as the tightness of the rewind. Heretofore, provision has been made for maintaining at a substantially constant level the initial preset output speed of the motor under varying load conditions. However, this arrangement does not serve to control the tension or velocity of the material or work, which increases with the increase in diameter of the rewound roll thereof.

Therefore, the primary object of the present invention is the provision of a motor control responsive both to the output speed of the motor under varying load conditions and to the velocity of the work.

Another object is the provision of means for maintaining the velocity of the Work at a constant level.

A further object is the provision of means for controlling the speed of rotation of a rewind or take-up roll as a function of the diameter of the rewound material.

The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings:

Fig. l is a more or less diagrammatic illustration of apparatus provided with the control of the present invention; and

Fig. 2 is a circuit diagram illustrating the control of the present invention.

Referring now to the drawings in detail, Fig. 1 diagrammatically iliustrates apparatus for unwinding material, such as for example, and not by way of limitation, paper from a supply roll or reel 10 thereof. It will be understood that the roll M is suitably mounted to freely rotate as the paper P is withdrawn therefrom. The paper is passed over a suitably mounted guide roller 12 and rewound upon a driven take-up or wind-up roll or reel 14 thereof. It will be understood that in its travel between the supply roll and the take-up roll, suitable mechanism (not illustrated) is provided so that the paper is subjected to a desired processing operation, for exice ample, and not by way of limitation, the paper may be coated with a suitable material, such as carbon, or the paper may be subjected to a printing operation, or other suitable operation. In order to rotate the take-up roll in the direction of the arrow 16, for re-winding the paper and for effecting the rotation of the supply roll in the direction of the arrow 18, for unwinding the latter therefrom, provision is made for a suitable drive-motor 20. As here shown, said motor is preferably an A. C. motor and is provided with the motor shaft 22. The take-up roll 14 is driven by an output shaft 24 which is coupled to the motor shaft 22 through the medium of the clutch mechanism 26.

The clutch mechanism 26 is preferably an electric slip coupling comprising eddy current clutch constituted by a drum 28 which is mounted on the motor shaft 22 and by a spider 30 which is mounted on the output shaft 24, said spider being disposed for rotation within the drum 28. It will be understood that the eddy current clutch 26 is of a type Well known in the art and therefore further illustration thereof is deemed to be unnecessary. Said clutch may be of the type manufactured by the Louis Allis Company, Milwaukee, Wisconsin. The spider 30 is provided with an excitation coil 31 (Fig. 2) and it will be understood that when said coil is energized the relative motion between the drum and the spider generates eddy currents in the drum which create an electromagnetic force and at full excitation cause the drum and spider to rotate at approximately the same relative speed. Moreover, it will be understood that as the excitation of the coil 31 is decreased, the speed of the output shaft 24 will be decreased.

Pursuant to the present invention, provision is made for a first A. C. control generator 32 having its rotor provided on the output shaft 24, so as to produce a signal voltage proportional to the speed of rotation of said shaft for maintaining the rotation of the output shaft 24 substantially at the initial pre-set starting speed thereof. In addition, provision is made for a second A. C. control generator 34 having its rotor 36 disposed for rotation by the paper moving between the feed supply roll 10 and the take-up roll 14. Therefore, it will be understood that the generator 34 produces a signal voltage which is directly proportional to the velocity or speed of travel of the paper between the rolls.

The operation of the control generators 32 and 34 will be explained in connection with the schematic circuit diagram in Fig. 2. The motor 29 is connected to a suitable source of A. C. power by the lines L1, L2 and L3. In order to provide for a direct current supply for the clutch coil 31, provision is made for the power transformer 38 having the primary 40 thereof connected to the power lines L2 and L3. The secondary 42 of said power transformer has one end thereof connected by the line L4 to the anode 44 of the main rectifier tube 46. Said tube is preferably a grid controlled, gas filled, half wave rectifier. The other end of the secondary 42 is connected by the line L5 to the anode 48 of the rectifier tube 56. A relay operated start switch 52 is inserted in the line L5. Sid line L5 is also connected through a clutchdamper control 54 to one end of the clutch coil 31, the other end of which is connected by the line L6 to the line L7. The secondary Winding 56 supplies the filament voltage for the rectifier tube 59 and the secondary winding 58 supplies the filament voltage for the rectifier tube 56, the line L7 being connected between said filament windings. The secondary so supplies the filament voltages for the various other tubes hereinafter referred to and the secondary 62 supplies the anode voltages for the duodiode 64. The rectifier tube 46 is energized alternately with the rectifier tube 50, the latter constituting a discharge tube. Said latter tube is both a continuation tube and a discharge tube for the direct current output of the main rectifier tube 46. The tube 46 conducts when the voltage applied to the plate 44 by the secondary 421ispositive toprovideacurrent fiow through-the coil 31*. from the negative )end to the positive (4-) end thereof for energizing said coil. During the time when said voltage on plate. 44-is negative, said tube does not conduct but the energy which has been stored in the clutch coil is dissipated as inverse energy through the discharge. tubev 50, said discharge tube serving the dual purpose of protecting the main rectifying tube d6 and at the same, time giving a discharge path for the energy created by the collapse of the fieldin the clutch coil 31, when the clutch is tie-energized.

The amount of the direct current flowingin the clutch coil is controlled by the grid 66 of the main rectifier tube 46. In order to establish a predetermined speed of. operation for the output shaft 24; provision is made for the rheostat 68 for supplying a predetermined bias voltage to the control. grid 66 of the main rectifier tube 46. By. varying the setting of rheostat 63, the initial starting speed of the output shaft-24 may be preset, as desired.

In addition to having the basic bias voltage developed across therheostat 63, there is also applied thereto-signal voltages representative of the speedofrotation of the output shaft 24 and of the paper velocity in travelling from the feed supply roll it to the take-up roll M. More specifically, it will be noted that the work or paper-generator M- is connected across the primary W) of the signalinput transformer 72. Therefore, it will be apparent that a voltage proportional to the speed or velocity of the paper, in its travel from the supply roll to the take-up roll, will be applied to the transformer '72. The motor.- output governor generator 32 has one end thereof connected directly to the primary 74 of a signal-input transformer/7'6. The other end of said generator is connected through the lead L8 to the center tap 77 of the secondary 78 of the transformer '72. The lead L9 interconnects the secondary78 and the primary 74, as illustrated. From the foregoing it will be apparent that a voltage representative of the paper velocity is coupled through a portion of the secondary '78, of the transformer 72, into the primary 74, of the transformer 76, which primary '74 also receives a voltage from the generator 32 which is representative of the speed of. rotation of the output shaft 24. The combined voltages from said sources are applied through the secondary 80 of the transformer '76 tot'ne anodes 82, $2 of the duo-diode-triode 84. The center tap 31' of the secondary 8t is connected through the rheostat 86 and the resistor 88 to one end of the previously mentioned rheostatfiS. it will be noted that the voltage regulator 9i) has its anode92 incircuit with the other end of rheostat 68, the cathode 94;- of. said regulator being connected tothecathode 95 of the tube at,

so that said voltage regulator 90 serves as a. coupling.

bridge between the output of the tube 84 and the input of the rectifier tube 46,.said. output being developed across the grid'bias rheostat 68.

Assuming now that the paper generator 34 is removed from the circuit so that the signal which is applied to the twin anodes 32-82 is responsive only to the output offthe governor generator 32, it will be apparent that if, with a change in the load, the speed of rotation of the shaft 24 increases beyond the pre-set speed, as predetermined by the setting of the rheostat 6%, an increased voltage will be developed by the generator 32 which will result in an increased negative voltage being developed across the. rheostat 68, whereby to decrease the current flow of the rectifier tube 4-6 so as to reduce the'D. C. current flowing in the clutch coil 31, whereby to reduce the output speed of the shaft 24. Therefore, it will be apparent.thatthesignal generator 32 servesas a governor formaintainingconstant thezoutput. speed ofthe shaftzZd' atathe. preset initial. velocity thereof despite variations in the load of the motor 20. However, as previously indicated, as the diameter of the paper on the take-up roll 14 increases, even though said roll is rotating at a constant speed, as governed by the generator 32, the paper velocity will be increasingwhereby to increase the paper tension and thetightness of the roll 14. The additional paper generator 34 serves to maintain said paper velocity at a constant level, whereby to prevent increased paper as a predetermined paper velocity. Thereafter, inthe.

event-that: the. speed, of operation of the output shaft 24 increases, whereby to increase paper velocity andv the:

tightness of the.re-wind,.it willbe apparent thatthe increased signal voltage generated by the generator 32 will tend todecrease the output of the rectifier tube 46, so as to reduce the speed of the shaft 24 to its preset speed.

In the event that the paper velocity increases due to increased-diameter of the take-up roll 14, the increased voltage output of the generator 34 will result in an increasednegative voltage being applied to the control grid 66-ofthe rectifier 46 whereby to reduce the speed of rotation of theoutputshaft 24 to provide the desired paper velocity and tightness ofre-wind. Therefore, it will be readilyapparent that as; the diameter of the take-up roll increases, the speed of operation of the output shaft 24 decreases, whereby to maintain the paper velocity at a constant. predetermined speed. will be understood that. the phase relationship of the gen-v erators 32 and 34 must be .so set that, as the paper speed increases, the voltage generated by the paper generator 34 tends to add to. the voltage generated by the motor generator 32, and'thereby to decrease the D. C. voltage applied to the clutch coil 31, whereby to decrease the speed of operation of the motor out-put shaft 24.

The previously mentioned tube 64 constitutes a full wave rectifier for supplying the anode voltage to the tubes 84, 93 and 100. Tube 98 is an electron-ray indicator tube, the grids thereof being connected through the lead.

L10 to the secondary 78 of the transformer 72, for indicatingthe operation of the generators 32 and 34. The,

primary 701 is connected through the lead L11 to the crystal rectifier 102 which is connected through the resistor-104 to the control grid 106 of the tube 100. Said tube controls the operation of a normally closed and normally de-energized relay 108 which is connected in the plate circuit of tube 100. Said relay, when energized, opens the power circuit for the motor 20 at 112, 114 and 116. It will be understood that the output of paper generator 34 charges condenser 110 to develop a voltage across the condenser which serves to bia the tube 100 to cut-off, so that the relay 108 remains closed. However, when there is no signal developed by the genera-tor 34, due tobreakage of the paper or as a result of any other cause which stop paper travel between the rolls, the condenser 110 dis-charges and the tube 100 conducts whereby toenergize the relay. This opens the motor circuit at 112, 114 and 116 so as to immediately stop the rotation of the roller-14.

From the foregoing, it will be readily apparent that due to the maintenance of a constant paper velocity, a uniform processing production is obtained, as well as a substantial increase inproduction. In addition the constant velocityof' the paper results in a constant degree of tension of the material inproduction, extreme sensitivity of operation. In addition automatic control which resultsinthe prevention of damage to the work is obtained;

While I'haveshown and described the preferred embodiment of. my invention, it will be understood that various changes may be-madein the present invention In this connection, it.

without departing from the underlying idea or principles of the invention within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

1. In apparatus of the character described, Work-drive means, means for obtaining a signal voltage as a function of the speed of said drive means, means for obtaining a signal voltage as a function of the velocity of the work in said apparatus, and means for utilizing said voltages to control the speed of said drive means, whereby to maintain said velocity substantially constant, said utilizing means including a pair of transformer each having a primary winding adapted to receive one of said voltages, respectively, and means for coupling the primary winding of one of said transformers and the secondary winding of the other of said transformers, Whereby to produce a composite control voltage, said voltage means having a phase relationship such that the voltages thereof are additive as said work velocity increases.

2. In apparatus of the character described, work-drive means, means for obtaining a signal voltage as a function of the speed of said drive means, means for obtaining a signal voltage as a function of the velocity of the work in said apparatus, and means for utilizing said voltages to control the speed of said drive means, whereby to maintain said velocity substantially constant, said utilizing means including a pair of transformers each adapted to receive one of said voltages, respectively, and means for coupling said transformers for producing a composite control voltage, said voltage means having a phase relationship such that the voltage thereof are additive as said Work velocity increases.

3. In apparatus of the character described, work-drive means, means for obtaining a signal voltage as a function of the speed of said drive means, means for obtaining a signal voltage as a function of the velocity of the work in said apparatus, a circuit operable by said voltages to control the speed of said drive means, said signal voltage means being connected in said circuit to provide a composite control voltage, and said signal voltage means being phased to provide for the addition of said signal voltages in response to an increase in the velocity of said work.

4. In a control system for a motor connected by an electric slip coupling in driving relation with a device disposed to wind material proceeding from a supply thereof, said coupling having a field winding, a control circuit to energize said field winding so as to adjust said coupling whereby to drive the winding device at a speed which will maintain substantially constant tension in said material as the winding diameter increases and as the speed of the material travel varies, said control circuit comprising means to generate a signal in response to the driving speed of the motor, means to generate a signal in response to the speed of travel of the material, and means to combine the outputs of said generating means to provide a composite signal voltage for operating said control circuit to energize said field winding, said signal generating means being phased to provide for the addition of said signal voltages in response to an increase in the velocity of the material, and said control circuit having means operable to decrease the energization of said field winding in response to an increase in said composite voltage.

5. A control system, as defined in claim 4, further characterized in that the control circuit includes rectifier means for energizing the field Winding of the slip coupling, said rectifier means comprising a grid-controlled rectifier tube, means providing a predetermined bias voltage for the grid of said tube whereby to control the output of said tube for energizing said field winding to provide a predetermined coupling between the motor and the winding device for a predetermined tension in said material, and means for varying said bias voltage in response to variations in the magnitude of said composite control voltage.

6. In a control system of the character described, a first and a second alternator means, a first transformer having its primary Winding electrically connected to the output of said first alternator means, a second transformer having its primary winding electrically connected to the output of said second alternator means, and the secondary winding of said second transformer being conneoted to the primary Winding of said first transformer, whereby to provide a composite signal at the secondary Winding of said first transformer.

'7. In a control system for a motor connected in driving relation with a device disposed to wind material pro ceeding from a supply thereof, a first generator driven by the material, a second generator driven by the motor, means for combining the outputs of said generators to produce a composite output, and means responsive to said composite output for controlling the driving speed of the motor whereby to maintain the velocity of the material substantially constant, said generators being phased to add the outputs thereof as the velocity of the material increases.

8. In a control system for a motor connected in driving relation with a device disposed to wind material proceeding from a supply thereof, a first generator driven by the material, a second generator driven by the motor, means for combining the outputs of said generators to produce a composite output, and means responsive to said composite output for controlling the driving speed of the motor whereby to maintain the velocity of the material substantially constant, said combining means including a pair of transformers each adapted to receive the output of one of said generators, respectively, the secondary of one of said transformers being coupled to the primary of the other of said transformers, and said generators having a phase relationship to add the outputs thereof as the velocity of the material increases.

9. In a control system for a motor connected in driving relation with a device disposed to wind material proceeding from a supply thereof, a first generator driven by the material, a second generator driven by the motor, means for combining the outputs of said generators to produce a composite output, and means responsive to said composite output for controlling the driving speed of the motor whereby to maintain the velocity of the material substantially constant, said generators being phased to add the outputs thereof as the velocity of the material increases, said controlling means including magnetic clutch mechanism for connecting the motor in said driving relation with the material-wind device, and means for varying the energization of said mechanism in response to variations in said composite output.

10. In a control system for a motor connected in driving relation with a device disposed to wind material proceeding from a supply thereof, a first generator driven by the material, a second generator driven by the motor, means for combining the outputs of said generators to produce a composite output, and means responsive to said compo-site output for controlling the driving speed of the motor whereby to maintain the velocity of the material substantially constant, said generators being phased to add the outputs thereof as the velocity of the material increases, and means for discontinuing the driving of the Winding device by the motor upon discontinuance of output by said first generator.

References Cited in the file of this patent UNITED STATES PATENTS 520,970 Scott June 5, 1894 2,305,937 Montgomery et al Dec. 22, 1942 2,469,706 Winther May 10, 1949 2,508,135 Baker May 16, 1950 2,523,046 Montgomery Sept. 19, 1950 2,684,458 Winchester July 20, 1954 2,688,111 Jones Aug. 31, 1954 

